Generally, it is desirable when flying a flag in the evening or night to illuminate the flag. In fact, Title 4 Chapter 1 of the United States Code specifically requires the U.S. flag to be illuminated when in darkness.
Traditionally, illumination has been provided by a spot light located on the ground proximate the base of a flag pole with the light source aimed at the flag. There are several problems associated with this approach. Most notably, the spot lights must be relatively high powered such that a suitable beam of light can be transmitted the entire distance from the light source to the flag which may be tens of feet in the air. As can be appreciated, these lights require significant amounts of energy that not only adds to the cost of flying a flag at night but also places added pressure on the Nation's already strained power grid.
Another problem associated with ground-based spot lights is that the lighting apparatus is generally stationary and as such it directs a highly directional unmoving beam of light. Flags on the other hand tend to move depending on the directionality of the wind. As such, when the wind is not coming from the typical prevailing direction for which the spot light is adjusted and aimed, all or part of the flag may not be illuminated.
To resolve the foregoing problems several solutions have been offered with varying degrees of success. Spot lights mounted on the flag pole itself are currently offered in the marketplace. Because these are located closer to the flag, they require less energy and are more efficient. They do not, however, solve the directional problem. Others have proposed mounting these light assemblies on swivels so that they track with the flag; however, the complexity of the hardware used to fly a flag increases substantially over a more traditional halyard configuration.
Others have suggested lights horizontally disposed over the flag wherein the flag is essentially draped from the rigid framework of the light assembly. This solution does provide for constant illumination at a reasonable light output but it cause the flag to fly in an unnatural manner that is not pleasing to many. Further, this solution does increase the complexity of the flag hanging hardware substantially.
Yet others have suggested providing flagpoles that have lighting assemblies incorporated therein that often send light rays emanating 360 degrees outwardly from the pole. Some references have suggested that a flag pole with a transparent portion adjacent the flag is used with a lighting assembly situated inside of the transparent portion. This has many problems not the least of which is the added expense of producing the relatively complex pole. With the light being directed 360 degrees, this design is not particularly efficient. Additionally, if only the top portion of the pole is transparent, a user cannot use the pole to fly a flag at night at half mast since that portion of the pole is unlikely to include an additional transparent illuminating section.